Convert SRP to use the new verbs DMA mapping functions for kernel
verbs consumers.
Signed-off-by: NRalph Campbell <ralph.campbell@qlogic.com>
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

Enable multiple concurrent connections to the same SRP target:

1) Use port GUID instead of node GUID in the initiator port
   identifier.  This allows connections to be made from multiple HCA
   ports at the same time.
2) Let the user specify the identifier extention when adding the
   device.  This allows userspace to make multiple connections even
   from the same port, if it wants too.

Without this, only one connection can be made from any given HCA, even
if it has multiple ports, because we don't use multi-channel mode, so
targets will only allow one connection from a given initiator port ID.
Signed-off-by: NIshai Rabinovitz <ishai@mellanox.co.il>
Signed-off-by: NMichael S. Tsirkin <mst@mellanox.co.il>
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

There has been a change in the format of port identifiers between
revision 10 of the SRP specification and the current revision 16A.

Revision 10 specifies port identifier format as

  lower 8 bytes :  GUID   upper 8 bytes :  Extension

Whereas revision 16A specifies it as 

 lower 8 bytes :  Extension  upper 8 bytes :  GUID

There are older targets (e.g. SilverStorm Virtual Fibre Channel
Bridge) which conform to revision 10 of the SRP specification.

The I/O class of revision 10 is 0xFF00 and the I/O class of revision
16A is 0x0100.

For supporting older targets, this patch:

1) Adds a new optional target creation parameter "io_class". Default
   value of io_class is 0x0100 (i.e. revision 16A)
2) Uses the correct port identifier format for targets with IO class
   of 0xFF00 (i.e. conforming to revision 10)
Signed-off-by: NRamachandra K <rkuchimanchi@silverstorm.com>
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

It's perfectly valid for a connection to an SRP target to have a
request limit of 0, so get rid of the message about it, which can spam
kernel logs even with printk_ratelimit().  Keep a count of such events
in a "zero_req_lim" SCSI host attribute instead, so someone who cares
can look at the statistics.
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

Make the sg_tablesize used by SRP adjustable at module load time via a
module parameter.  Calculate the corresponding IU length required to
support this.
Signed-off-by: NVu Pham <vu@mellanox.com>
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

The SRP driver never sleeps while holding target_mutex, and it's just
used to protect some simple list operations, so hold times will be
short.  So just convert it to a spinlock, which is smaller and faster.
Signed-off-by: NMatthew Wilcox <matthew@wil.cx>
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

Create an SRP FMR pool on HCAs that support FMRs, and use FMRs to map
gather/scatter lists that have more than one entry into a single
memory region that appears virtually contiguous to the SRP target
(which is the RDMA initiator).

This patch bails out on FMR mapping for SCSI commands where the
gather/scatter list cannot be mapped into a single FMR because there
are sub-page-sized entries in middle of the list.  An unaligned
start or end of the list is OK.

Based on a patch by Vu Pham <vuhuong@mellanox.com>.
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

If a SCSI abort completes, or the command completes successfully, then
the driver must remove the command from its queue of pending
commands.  Similarly, if a device reset succeeds, then all commands
queued for the given device must be removed from the queue.
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

Since the SCSI midlayer is moving towards entirely getting rid of
commands with use_sg == 0, we should treat this case as an exception.
Therefore, change the IB SRP initiator to create a fake scatterlist
for these commands with sg_init_one().  This simplifies the flow of
DMA mapping and unmapping, since SRP can just use dma_map_sg() and
dma_unmap_sg() unconditionally, rather than having to choose between
the dma_{map,unmap}_sg() and dma_{map,unmap}_single() variants.
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

Convert srp_host->target_mutex from a semaphore to a mutex.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

Increase SRP max_luns to 512 to match the kernel's default, since SRP
storage targets can have lots of LUNs and the SRP initiator itself
doesn't have any particular limit.
Signed-off-by: NRoland Dreier <rolandd@cisco.com>

Add an InfiniBand SCSI RDMA Protocol (SRP) initiator.  This driver is
used to talk talk to InfiniBand SRP targets (storage devices).
Signed-off-by: NRoland Dreier <rolandd@cisco.com>